Cucumber mosaic virus in narrow-leafed lupins

Page last updated: Wednesday, 9 May 2018 - 3:45pm

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Cucumber mosaic virus (CMV) is a seed- and aphid-borne virus that infects narrow-leafed lupins. It can also infect many other broad-leafed plant species. In the wheatbelt the principal infection source for lupin crops is sowing infected lupin seed. Wheatbelt regions most at risk are the high rainfall zones of the northern and central agricultural region and the south coastal region.


CMV infection causes lupin leaves to become pale, bunched and down curled with faint mosaic. In plants that grow from infected seed, all leaves develop these symptoms and these plants are severely stunted. Healthy plants that become infected during the growing season have pale, bunched young leaves with faint mosaic while older leaves formed prior to infection appear normal. As growth continues, all new leaves show symptoms and the infected plants become stunted. The earlier a plant becomes infected, the fewer the pods set, the smaller the size of seed produced and the smaller the yield. With late infections symptoms are restricted to tip leaves.

Current season infection with Cucumber mosaic virus in narrow leafed lupin
Current season infection with cucumber mosaic virus in narrow leafed lupin. Lower leaves are normal looking, while leaves at growing tip are pale, bunched and down curled
Seed-borne infection with CMV in narrow-leafed lupin plants.
Seed-borne infection with CMV in narrow-leafed lupin plants. Plants are stunted with bunched, down curled and mottled leaves

Sources of virus

Sowing infected seed produces infected seedlings scattered at random within the crop. Aphids pick up the virus from the infected plants and spread it to nearby healthy plants. When infection incidence reaches 100%, the maximum possible seed transmission rate to seedlings varies with lupin variety.

In the wheatbelt, although infected lupin seed is the only CMV source of consequence for lupin crops, other legume hosts can become infected, including clovers, chickpea, faba bean, lentil and field pea. Weeds that sometimes become infected include capeweed, stagger weed and fumitory, but the virus is not seed-borne in these species so infection is lost over summer.

Aphid vectors

CMV is spread by many aphid species, including green peach (Myzus persicae), blue green (Acyrthosiphon kondoi) and cowpea (Aphis craccivora) aphids that colonise lupins as well as migrants of common non-lupin colonising species, especially oat (Rhopalosiphum padi) and turnip (Lipaphis erysime) aphids. CMV is transmitted non-persistently: an aphid picks it up within one to two seconds while probing an infected plant, but the virus is then lost again when the aphid probes one or two healthy plants.


Brenda Coutts